Persistence of the Co-tetra-phenyl-porphyrin HOMO-LUMO features when a single organic layer is grown onto Cu(1 1 0)-(2 × 1)O

Ultra-thin organicfilms must be screened when deposited onto freshly prepared metal surfaces in view ofpreserving the molecular physical-chemical properties. A current promising strategy prescribes the oxidation ofthe substrate and, when possible, the creation of a single oxide layer. This strategy was successfully exploitedwith metal-tetra-phenyl porphyrins (M-TPP) on Fe(0 0 1)-p(1 × 1)O. Here, our study is extended to the oxidizedCu(1 1 0)-(2 × 1)O. Having free coordination sites, the Co-TPP is perturbed when deposited onto the freshlyprepared copper surface and the HOMO-LUMO levels quenched, as reported in the literature. Here, we provethat the oxide copper surface reduces the molecule-substrate interaction and photoemission spectroscopy is ableto reveal the characteristic electronic features of the molecules.